1. The Field of the Invention
The present invention relates to tethered implants and systems for mounting on a natural or resected articulation surface of an orthopedic joint of a patient.
2. The Relevant Technology
The human body has a variety of movable orthopedic joints such as the knee joint, hip joint, shoulder joint, and the like. These joints are formed by the intersection of two bones. The intersecting end of each bone has smooth articular surface that is comprised of cartilage. As a result of injury, wear, arthritis, disease or other causes, it is occasionally necessary to replace all or part of an orthopedic joint with an artificial implant. This procedure is referred to as a joint replacement or arthroplasty. For example, a total knee arthroplasty comprises cutting off or resecting the articular surfaces at both the distal end of the femur and the proximal end of the tibia. Complementary artificial implants are then mounted on the distal end of the femur and the proximal end of the tibia. Where only a portion of a joint is damaged, a partial joint arthroplasty can be performed. In this procedure, one or more artificial implants replace only a portion of a joint.
Although joint replacement is now a common procedure that has met with popular success, conventional implants and related mounting techniques have significant shortcomings. One significant drawback of many joint replacements is the extended and painful patient recovery. For example, a traditional knee replacement requires an open procedure wherein a relatively large incision is made which severs a portion of the muscle bounding the femur. The large incision is made so as to fully expose the respective ends of the femur and tibia.
This exposure is necessary when using conventional techniques to resect the femur and tibia and to mount the implants. For example, some conventional tibial implants are screwed directly into the resected end face of the tibia. Mounting such screws requires exposure of the resected end face. In yet other embodiments, the implants are formed with posts projecting therefrom. The posts are received within sockets formed on the resected end face of the tibia and femur. Again, forming of the sockets and inserting the posts into the sockets requires substantially full exposure of the resected end face of the tibia and femur.
In general, the more invasive the surgery, the more painful, difficult, and time consuming the patient recovery. This is largely due to the significant amount of scar tissue produced by the incision and resection of various soft tissues. Furthermore, such open and invasive surgeries have a greater risk of infection.
Another problem with conventional joint implants and related techniques for mounting is that it can be difficult to fit, adjust, and/or exchange different implants during the fitting stage. That is, implants come in a variety of different sizes, shapes, and configurations. During the joint procedure, the surgeon may often test a variety of different sized implants to determine the best fit and alignment. As conventional implants are screwed into or pounded onto the bone during placement, the fitting, adjustment, and/or replacement of different conventional implants can be difficult and potentially damaging to the bone. Likewise, it can often be difficult to replace worn or damaged implants.
Accordingly, what is needed are implants and related methods and systems for preparing an articular surface of a joint and mounting an implant thereat which minimizes the length of incision, the amount of bone resection, and/or the impact on soft tissue. What is also needed are implants and related methods and systems which enable easier fitting, alignment, testing, and/or replacement of implants.